Java tutorial
/* * Copyright (C) 2013 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package cn.edu.wyu.documentviewer; import static cn.edu.wyu.documentviewer.DocumentsActivity.TAG; import static cn.edu.wyu.documentviewer.DocumentsActivity.State.MODE_UNKNOWN; import static cn.edu.wyu.documentviewer.DocumentsActivity.State.SORT_ORDER_DISPLAY_NAME; import static cn.edu.wyu.documentviewer.DocumentsActivity.State.SORT_ORDER_LAST_MODIFIED; import static cn.edu.wyu.documentviewer.DocumentsActivity.State.SORT_ORDER_SIZE; import static cn.edu.wyu.documentviewer.DocumentsActivity.State.SORT_ORDER_UNKNOWN; import static cn.edu.wyu.documentviewer.model.DocumentInfo.getCursorInt; import java.io.FileNotFoundException; import org.apache.commons.io.IOUtils; import android.content.AsyncTaskLoader; import android.content.ContentProviderClient; import android.content.ContentResolver; import android.content.Context; import android.database.Cursor; import android.net.Uri; import android.os.CancellationSignal; import android.os.OperationCanceledException; import android.provider.DocumentsContract; import android.provider.DocumentsContract.Document; import android.util.Log; import cn.edu.wyu.documentviewer.DocumentsActivity.State; import cn.edu.wyu.documentviewer.RecentsProvider.StateColumns; import cn.edu.wyu.documentviewer.model.DocumentInfo; import cn.edu.wyu.documentviewer.model.RootInfo; class DirectoryResult implements AutoCloseable { ContentProviderClient client; Cursor cursor; Exception exception; int mode = MODE_UNKNOWN; int sortOrder = SORT_ORDER_UNKNOWN; @Override public void close() { IOUtils.closeQuietly(cursor); ContentProviderClient.releaseQuietly(client); cursor = null; client = null; } } public class DirectoryLoader extends AsyncTaskLoader<DirectoryResult> { private static final String[] SEARCH_REJECT_MIMES = new String[] { Document.MIME_TYPE_DIR }; private final ForceLoadContentObserver mObserver = new ForceLoadContentObserver(); private final int mType; private final RootInfo mRoot; private DocumentInfo mDoc; private final Uri mUri; private final int mUserSortOrder; private CancellationSignal mSignal; private DirectoryResult mResult; public DirectoryLoader(Context context, int type, RootInfo root, DocumentInfo doc, Uri uri, int userSortOrder) { super(context, ProviderExecutor.forAuthority(root.authority)); mType = type; mRoot = root; mDoc = doc; mUri = uri; mUserSortOrder = userSortOrder; } @Override public final DirectoryResult loadInBackground() { synchronized (this) { if (isLoadInBackgroundCanceled()) { throw new OperationCanceledException(); } mSignal = new CancellationSignal(); } final ContentResolver resolver = getContext().getContentResolver(); final String authority = mUri.getAuthority(); final DirectoryResult result = new DirectoryResult(); int userMode = State.MODE_UNKNOWN; // Use default document when searching if (mType == DirectoryFragment.TYPE_SEARCH) { final Uri docUri = DocumentsContract.buildDocumentUri(mRoot.authority, mRoot.documentId); try { mDoc = DocumentInfo.fromUri(resolver, docUri); } catch (FileNotFoundException e) { Log.w(TAG, "Failed to query", e); result.exception = e; return result; } } // Pick up any custom modes requested by user Cursor cursor = null; try { final Uri stateUri = RecentsProvider.buildState(mRoot.authority, mRoot.rootId, mDoc.documentId); cursor = resolver.query(stateUri, null, null, null, null); if (cursor.moveToFirst()) { userMode = getCursorInt(cursor, StateColumns.MODE); } } finally { IOUtils.closeQuietly(cursor); } if (userMode != State.MODE_UNKNOWN) { result.mode = userMode; } else { if ((mDoc.flags & Document.FLAG_DIR_PREFERS_GRID) != 0) { result.mode = State.MODE_GRID; } else { result.mode = State.MODE_LIST; } } if (mUserSortOrder != State.SORT_ORDER_UNKNOWN) { result.sortOrder = mUserSortOrder; } else { if ((mDoc.flags & Document.FLAG_DIR_PREFERS_LAST_MODIFIED) != 0) { result.sortOrder = State.SORT_ORDER_LAST_MODIFIED; } else { result.sortOrder = State.SORT_ORDER_DISPLAY_NAME; } } // Search always uses ranking from provider if (mType == DirectoryFragment.TYPE_SEARCH) { result.sortOrder = State.SORT_ORDER_UNKNOWN; } Log.d(TAG, "userMode=" + userMode + ", userSortOrder=" + mUserSortOrder + " --> mode=" + result.mode + ", sortOrder=" + result.sortOrder); ContentProviderClient client = null; try { client = DocumentsApplication.acquireUnstableProviderOrThrow(resolver, authority); cursor = client.query(mUri, null, null, null, getQuerySortOrder(result.sortOrder), mSignal); cursor.registerContentObserver(mObserver); cursor = new RootCursorWrapper(mUri.getAuthority(), mRoot.rootId, cursor, -1); if (mType == DirectoryFragment.TYPE_SEARCH) { // Filter directories out of search results, for now cursor = new FilteringCursorWrapper(cursor, null, SEARCH_REJECT_MIMES); } else { // Normal directories should have sorting applied cursor = new SortingCursorWrapper(cursor, result.sortOrder); } result.client = client; result.cursor = cursor; } catch (Exception e) { Log.w(TAG, "Failed to query", e); result.exception = e; ContentProviderClient.releaseQuietly(client); } finally { synchronized (this) { mSignal = null; } } return result; } @Override public void cancelLoadInBackground() { super.cancelLoadInBackground(); synchronized (this) { if (mSignal != null) { mSignal.cancel(); } } } @Override public void deliverResult(DirectoryResult result) { if (isReset()) { //IOUtils.closeQuietly(result); result.close(); return; } DirectoryResult oldResult = mResult; mResult = result; if (isStarted()) { super.deliverResult(result); } if (oldResult != null && oldResult != result) { //IoUtils.closeQuietly(oldResult); oldResult.close(); } } @Override protected void onStartLoading() { if (mResult != null) { deliverResult(mResult); } if (takeContentChanged() || mResult == null) { forceLoad(); } } @Override protected void onStopLoading() { cancelLoad(); } @Override public void onCanceled(DirectoryResult result) { //IoUtils.closeQuietly(result); result.close(); } @Override protected void onReset() { super.onReset(); // Ensure the loader is stopped onStopLoading(); //IoUtils.closeQuietly(mResult); mResult.close(); mResult = null; getContext().getContentResolver().unregisterContentObserver(mObserver); } public static String getQuerySortOrder(int sortOrder) { switch (sortOrder) { case SORT_ORDER_DISPLAY_NAME: return Document.COLUMN_DISPLAY_NAME + " ASC"; case SORT_ORDER_LAST_MODIFIED: return Document.COLUMN_LAST_MODIFIED + " DESC"; case SORT_ORDER_SIZE: return Document.COLUMN_SIZE + " DESC"; default: return null; } } }